For sure a bad design!
Here in Germany a manufacturer has to withstand a certificate that makes any change on engine, suspension etc. street legal.
This especially means you cannot mount anything anywhere.
In this case SM should have known better, as they are the experts on their builds. Especially regarding weight and
I do know that e.g. MAN, but also Mercedes, Iveco etc. have their Guidelines
to fitting bodies. I think Ford does so as well?
These truck guidelines do NOT allow to bore or install anything at the lower parts of a "C" Channel letter frame, afaik.
Though Germany is very picky on this ;-)